Michael Jackson, the self-styled King of Pop, who has died suddenly aged 50 after being taken to hospital in Los Angeles, was music royalty – one of its biggest stars and holder, for Thriller, of the record for the best-selling album in history. Eventually, however, his bizarre life-style and personal notoriety eclipsed his talent and his numerous achievements.

Fame, from the age of 11, when he was lead singer of the first black boy band, the Jackson Five, had such a damaging effect that his life was permanently affected. A combination of dysfunctional family and invasive fame ate away at the essentially private singer, whose initially minor eccentricities escalated into grotesque changes to his appearance and lifestyle. Ultimately, it led to accusations of paedophilia and a criminal prosecution.

If ever there was an illustration of the adage that celebrity destroys what it touches, Jackson was it. Highly sensitive and impressionable, he was unsuited to fame – ironic, given that his became one of the most recognised faces in the world. Despite loving the razzle-dazzle of performance – even his off-duty wardrobe, with its epauletted jackets, looked like stagewear – he was crushed by the pressure of maintaining a cherubic public persona. He probably would have been happiest working behind the scenes, in the mode of his collaborator and mentor, Quincy Jones, producer of the 50m-selling Thriller.

Jackson's success deprived him of his childhood – at least, that was the stock explanation for his more outlandish behaviour. From the age of 10, he spent most of his time recording and touring, and consequently spent the rest of his life yearning for what he thought he had lost. As an adult he attempted to recreate the lost childhood, enabled by a fortune that was at one time estimated to be in the hundreds of millions of dollars.

He indulged himself by turning his California ranch Neverland into a funfair, complete with zoo, over which he presided, dressed in his toy-soldier gear. His closest friendships were with fellow ex-child star Elizabeth Taylor, a chimpanzee called Bubbles, who travelled with him till it grew too large and dangerous, and, ambiguously, with children. He once said that if there were no children in the world, he would have no reason to exist.

His bond with them influenced almost everything he did. He worked extensively with underprivileged youngsters, opening Neverland to them and even taking one or another favoured child on tour. He had a great interest in young people from all over the world, even once proposing to adopt a boy and a girl from each continent.

At the 1996 Brit Awards he was accompanied on stage by a children's choir, prompting a stage invasion by Jarvis Cocker of Pulp, who claimed his attitude was "Messiah-like". (Sidestepping the accusation, Jackson claimed Cocker was just jealous of his popularity.) His relations with kids were healthy, Jackson argued – he was simply attracted by their "purity and innocence".

The same qualities were attributed to him by his extraordinarily loyal fans. Jackson was, in their view, grievously maligned – a saintly character whose good intentions were distorted by a malicious press. During pre-trial hearings of his child-molestation case in 2004, fans outside the court waved banners reading "Innocent Until Proved Innocent". Journalists who wrote negatively about Jackson could expect a bombardment of angry letters.

He was born in Gary, Indiana, (within weeks, coincidentally, of his main 1980s rivals and fellow Midwesterners Madonna and Prince). He, his parents and eight siblings squeezed into a two-bedroom house on a street that was later renamed Jackson Boulevard in their honour. Coached by his father Joe, a steel-mill worker, Michael and older brothers Jermaine, Marlon, Jackie and Tito formed a singing group. Despite shyness that he never overcame, he was a natural singer and dancer, and took to the frontman role with relish. By the age of six, the young Jacksons were playing strip clubs and burlesque palaces - the only venues open to them in Gary.

Joe was a disciplinarian who ruled the family with an iron rod. The brothers, who were brought up as Jehovah's Witnesses, were not allowed to visit friends, and were made to rehearse into the night. In adulthood, Michael revealed that his father beat him for the most minor transgressions, so terrifying him that "there were times when he'd come to see me and I would start to be sick."

Tito claimed Michael's dance routines evolved from the fancy footwork he employed dodging his father's fists. In a 2003 TV interview, Joe claimed his son had exaggerated: "I whipped him with a switch and belt, [but] I never beat him. You beat someone with a stick." He averred that the whippings had made him "one of the best artists in the world". Joe also taunted him about his "ugliness" and adolescent skin problems, sowing self-doubt that later manifested itself in cosmetic surgery fixation.

The child group made their name in the Midwest, and by 1968 came to the attention of Motown Records. Michael was by then an obvious star-in-waiting, a 10-year-old with an unusually adult feel for soul music. His singing was at once poised and youthfully exuberant, his dancing fluid and instinctive. Motown president Berry Gordy said of his first glimpse of Michael: "He sang his songs with such feeling, inspiration and pain – like he had experienced everything he was singing about."

The Jackson Five's first Motown single, I Want You Back, reached number one in America (as would their next three singles) in 1969. The youthful band were an instant hit with prepubescent girls - mainly black girls, but also some white ones. Michael, the particular object of their desire, had just turned 11, and would never be able to walk down the street unrecognised again.

The band's working life was brutal: when they were not in studios they were on tour, sometimes playing 45 shows in 90 days. As lead singer, Michael's schedule was more onerous than that of his brothers. After three hours' daily tutoring, he spent the rest of the day recording the 13 albums the Jacksons released for Motown between 1969 and 1975. From the studio window he watched ordinary children playing, and would "always cry from loneliness".

Groomed for a solo career, he started to make recordings outside the band that were released concurrently with Jackson Five material. He was as popular a solo act as he was a band member – almost uniquely for a child star, he retained his popularity even when his voice changed. That said, his first few solo records as a 13-year-old were nothing special, a case in point being his sugary ode to a rat named Ben. Young adulthood was when he came into his own and became, as Taylor apparently first dubbed him, King of Pop.

Finally free of his father and of Motown, and working closely with Quincy Jones, whom he had met while playing the Scarecrow in the 1978 film The Wiz, his commercial-pop genius was realised. He had half a decade of extraordinary creativity that yielded two epochal albums, 1979's Off the Wall and 1982's Thriller. These transformed him from teen idol to boundary-crossing superstar.

Though still committed in 1979 to the Jacksons (the "Five" having been dropped) for recording work, he put all his energies into Off the Wall. It heralded his arrival as a major star. Released just before his 21st birthday, it portended the dominance of R&B – especially Jackson's style of supremely slick, catchy R&B – in the charts throughout the 1980s and 90s. It was the first American album to produce four No 1 singles, and sold 7m copies in America alone. The gruelling work schedule that exacted such a price during his childhood had also honed his musical skills, and he was at the top of his game. Thriller was the one that broke all records and turned him into a phenomenon. No 1 for 37 weeks in the US, it went on to win eight Grammy Awards and sell an estimated 50m copies.

Jackson's stroke of inspiration was to fuse black R&B and white rock – something that is now routine, but had not at that point been attempted by a big-name pop act. MTV, which had hitherto rarely aired black acts, seized on the album's singles such as Billie Jean and Beat It and played them to death. Jackson even threw in a little something for the parents, a duet with Paul McCartney. That friendship ended acrimoniously when Jackson outbid McCartney when the Beatles' publishing catalogue came up for sale in 1985 – essentially, Jackson now owned all of McCartney's 1960s songs. The purchase, for several hundred million dollars, was one of his more astute.

Later, he would fritter away a large part of his fortune on never-realised projects such as a theme park dedicated to racial harmony. He also developed a taste for enormously expensive and tasteless furnishings, reportedly spending up to a million dollars a time in Las Vegas's shopping malls.

The photo of him on the cover of Thriller was the last album sleeve on which he looked what he was: a young male with perceptibly African-American features. Around that time, his skin colour began subtly to lighten. He claimed it was caused by the pigmentation disorder vitiligo, but rumours suggested he had bleached his skin. His features also began to be altered by plastic surgery. His nose slimmed down, a cleft appeared in his chin, his eyelids reputedly were lifted and his lips thinned.

As his appearance changed, rumours about his lifestyle proliferated. Jackson supposedly slept in an oxygen tent, clothed Bubbles in matching outfits, and offered to buy the Elephant Man's bones. He began to appear in public wearing a surgical mask, and seemed to be asexual, with no significant relationships during his 20s.

That changed in 1994, when he married Elvis Presley's daughter, Lisa Marie, a union that lasted two years and excited a great deal of speculation. The year before, Jackson had been accused of sexually molesting a 13-year-old boy, tipping him into the worst crisis of his personal and professional life to that point. He eventually settled out of court, paying the boy millions in return for dropping the case, but his career never quite recovered. It was rumoured that the marriage was an attempt to normalise his image. Instead, he seemed all the stranger.

His second marriage, to his dermatologist's nurse, Debbie Rowe, in 1996, was equally perplexing to everyone but the couple themselves. They seemed to spend little time together, but Rowe produced his first two children, son Prince Michael and daughter Paris. They divorced in 1999. A third child, Prince Michael II, was born with the aid of a surrogate mother. Despite Jackson's great affinity with children, his behaviour with his own was eccentric.

He forced them to wear masks or veils whenever they appeared in public, supposedly to preserve their privacy; a few photos exist of the children without their cover-ups, and their lack of a physical resemblance to Jackson is marked.

Jackson's career slowly recovered from the abuse scandal, and his next studio albums, HIStory and Invincible (the latter, released in 2001, was his last album of original material), were chart-topping hits, though by then he was treading water musically. Despite the enormous influence he had had on pop, hip hop and R&B, by the late 90s he was producing nothing of much note.

In the mid-00s, funded by his friend Sheikh Abdullah of Bahrain, he reportedly began work on what would have been his first new album in five years. He had struck a deal with Abdullah, who wrote songs as a hobby, whereby Jackson would record some of the songs in return for the sheikh paying recording costs. As with so many of Jackson's business deals, it came to nothing: the pair fell out and Abdullah apparently tried to sue Jackson to recover his money.

Jackson's final years were marked by financial troubles and a second, even more damaging, child-abuse scandal. In a 2003 documentary for Granada TV, Living with Michael Jackson, the singer told journalist Martin Bashir that he often shared his bedroom with young child "friends," one of whom, a 12-year-old, appeared in the programme holding hands with Jackson. This led to Jackson being charged with seven counts of child abuse, and a trial that transfixed both the media and fans until he was acquitted five months later.

Despite the innocent verdict, it was essentially downhill from there. He moved to Bahrain and embarked on the ill-fated album; back in America, his finances were in a tangle that kept the lawyers busy. He had lived beyond his means for years, and was also coming up against the matter of a $270m loan from Bank of America that he found difficult to repay. The title to his beloved Neverland ranch, vacant and crumbling since the move to Bahrain, hung in the balance. Restructuring his debt, he hung onto the ranch by the skin of his teeth.

After years away from live performance, Jackson was due to come back in grand style next month, with a massive series of dates at London's 02 Arena. Tickets for the 50 shows sold out instantly, proving that thousands of people were still lured by the promise of the old stardust.

Even then, there were wild stories: one persistent one was that Jackson, who had been looking increasingly frail and was said to be suffering from skin cancer, was only contractually obliged to appear onstage for 13 minutes at each show. Like so much else about him, it may have been true, but it was probably just razzle-dazzle. His children survive him.

•Michael Jackson, pop musician, born 29 August 1958; died 25 June 2009

• This article was amended on 26 June 2009. The original gave Michael Jackson's birth date as 26 August 2009. This has been corrected.